To learn how environmental contaminants affect health, researchers rely on biomonitoring of blood, urine, and other tissues, and sampling in personal spaces, such as testing dust and air in homes. Study participants often want to learn their own results. Yet exposure measurements for emerging contaminants, such as many endocrine disrupting compounds (EDCs) precede understanding of the health implications, exposure sources, and strategies for exposure reduction; so researchers face challenges in communicating results. Interviews and a workshop with researchers and study participants revealed that challenges include tailoring report-back to individual and cultural differences, including science literacy; reporting complex results for many analytes without overwhelming; providing contextual information to explain the relevance to health and effective choices for action; and supporting scalability for large studies without becoming impersonal or burdening the researcher. These issues can be addressed by a user-centered personalized digital report-back interface. The consortium will (1) gain insights into mental models, abilities, and preferences of study participants; (2) use this knowledge to develop an interface that effectively communicates individual results, builds understanding and trust in the research process, and communicates contextual knowledge about EDCs to inform and motivate evidence-based health-protective action; and (3) field test digital report-back in a Centers for Disease Control study in public housing, an underserved environmental justice population. The project consortium is transdisciplinary and multi-institutional and integrates knowledge and methods from environmental health science, social science, and computer science. To design effective communications, the project uses interviews with study participants to elicit information about conceptualizations of EDCs and the correspondence between participants' understandings/misunderstandings and researchers' intended messages. To design the user interface, the project uses the human-computer interaction methods of Contextual Design, which relies on observations and iterative paper-prototyping and usability testing, and Value Sensitive Design, which involves interviews to reveal both predominant and minority values that affect adoption of the interface. Paper and digital report-back materials will be developed for the CDC Green Housing Study, with modules for reporting on pesticides and phthalates in dust and urine, and report-back will be fielded in the GHS. Interviews will be conducted with Green Housing Study (GHS) participants after they received paper or digital reports in order to compare experiences with these methods. Past evaluations have shown that effective report-back can increase environmental health literacy, increase trust in research and pride in participating in science, and motivate action to reduce environmental exposures and protect health. Results of this project will provide guidance for major NIEHS cohort studies and the California Biomonitoring Program, which is required by law to report individual results. PUBLIC HEALTH RELEVANCE: Environmental health research depends on biomonitoring and personal exposure studies that test for a wide range of chemicals for which the health effects are not yet known. Previous research shows that participants want to receive their own results, and can understand and use them; but researchers need better tools to ethically and effectively communicate unfamiliar information to diverse participants. This project will develop a personalized digital interface to report individual results using methods that respond to individual and cultural needs, preferences, and values; and it will field test the report-back tool in an epidemiologic study in public housing.